Electrical energy from a multi-cell battery pack is used to energize an electric machine in a variety of systems. For instance, in a vehicle having an electrified powertrain, stator windings of an electric machine may be energized by a battery pack to generate output torque. The generated output torque can be delivered to one or more drive axles to propel the vehicle, e.g., a road vehicle, train, or boat. In other systems, such as power plants, construction equipment, robots, certain appliances, and other types of vehicles such as aircraft, motor torque can be used to perform a host of useful work tasks.
A particular type of battery pack uses a reinforced separator positioned within an electrolyte solution between an anode and a cathode, all of which is contained within a polymer-coated aluminum pouch. Tabular extensions of the anode and cathode are ultrasonically welded or otherwise conductively joined to a conductive interconnect member to construct a module of the battery pack. Multiple modules of the same or a different number of battery cells may be electrically interconnected to construct the battery pack, with the actual number of such modules varying with the power requirements of the particular application.
Individual battery cells tend to slowly degrade over time. As a result, electrical parameters such as open circuit voltage, cell resistance, and state of charge may change over time relative to calibrated/new values. In order to ensure accurate ongoing monitoring of the health and available charge of the battery pack, individual cell voltages are typically measured and reported to a battery controller. The measured cell voltages are thereafter used to perform a variety of different battery circuit diagnostics and electric range calculations. As a result, a sensing fault in which the cell voltages become unavailable can result in the controller being temporarily unaware of the true state of the battery pack.